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HelpTest Code LAB3532 Unfractionated Heparin Activity
Clinical System Name
Unfractionated Heparin Activity
Sample Requirements
Specimen: Whole Blood
Container(s): Lt. Blue/Citrate
Required Vol: one 1.8 mL tube or one 2.7 mL tube (do NOT over or under fill)
Minimum Vol: N
Note: This is enough for a PT, PTT, HEP UNF, and Fibrinogen on the same sample. Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume. Use of a Vascular Access Device for the collection of coag testing is not recommended.
Please review the Anticoagulant Job Aid for additional collection instructions for patients with lines.
Processing Instructions
Main Campus CPA: Core Technologist will process specimen. Deliver blood directly to Core Coag bench.
Reject due to: Clotted, Hemolyzed, Insufficient quantity (underfill), or Improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: Core 14 Freezer ( -70 C).
Core Technologist: Specimen should be centrifuged within 1 hour of collection. Spin whole blood, remove plasma. Transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label.
Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note the fill line on the tube. Use of a Vascular Access Device for the collection of coag testing is not recommended. If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be transferred to the Lt Blue/Citrate tube by use of the blood transfer device.
Specimen should be centrifuged within 1 hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Freeze until solid one aliquot of 1.0 mL plasma in plastic tube at -70C (preferred) or -20C.
Non-Children's Hospital Off-site collection: Ship completely frozen on dry ice.
Children's Regional Clinics: Ship completely frozen in frozen Nalgene Labtop cooler with ice pack inside an insulated soft cooler.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Citrated platelet-poor plasma | Room temp | ≤4 h |
| Refrigerated | N | |
| Frozen -20 C or -70 C | ≤3 m |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Coagulation
Phone Number: 206 987-2617 (Client Services)
Synonyms
LAB3532
anti-Xa activity
HEP UNF
Heparin Activity Unfractionated
Heparin Unfractionated
UFH
Description
Unfractionated heparin (UFH) is used for the prevention and treatment of thromboembolic diseases. The quantitative determination of plasma unfractionated heparin levels is useful for monitoring treatment efficacy.
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y |
Daily |
1 h |
Methodology
Method: Chromogenic Substrate by STA-R MAX
Analytical Volume: 1 mL plasma
This is enough for a PT, PTT, HEP UNF, and Fibrinogen on the same sample.
Limitations: This assay requires antithrombin III (ATIII) in patient's plasma. Low level of ATIII may underestimate the heparin level.
Results affected by moderate lipemia, moderate hemolysis, and moderate icterus.
High hematocrit greater than or equal to 56% requires a citrate adjusted tube.
Therapeutic Range
The therapeutic range for Unfractionated Heparin Activity is 0.3 - 0.6 Anti-Xa IU/mL.
Heparin activity is reported in Anti-Xa IU/mL (Anti-Xa International Units/mL).
CPT Codes
85520
Critical Values
Greater than or equal to 1.10 International Units/mL